In many clinical situations, blood vessels are occluded with various implants to control bleeding, prevent blood supply to tumors, block blood flow within an aneurysm or other vascular malformations. Intracranial aneurysms, for example, may rupture causing significant bleeding. The significant bleeding may permanently damage the surrounding brain tissue, possibly causing serious injury and death. Intracranial aneurysms may be particularly difficult to access and treat when they are formed in remote cerebral blood vessels. If left untreated, hemodynamic forces of normal pulsatile blood flow can rupture fragile tissue in the area of the aneurysm causing a stroke.
Various implants have been used to occlude vascular sites. For example, vaso-occlusive devices are surgical implants that are delivered through a catheter in a blood vessel or vascular cavity and placed within aneurysm to form a thrombus and occlude the aneurysm. In one conventional system, a guide wire is inserted through a vascular cavity. An outer catheter or sheath is guided by the wire and inserted through the vascular cavity, and the implant is pushed or otherwise forced through the interior of the catheter to an aneurysm site.
Conventional implant delivery systems, however may exhibit a number of problems as a result of a gap between the guide wire and the outer sheath. First, while the guide wire may be able to turn and maneuver through curved vascular cavities or cavity divisions, such as a “Y” section or other division that splits a blood vessel, the outer sheath that follows the guide wire may not be able to complete these maneuvers. For example, if a blood vessel makes a sharp turn, the outer portions of the distal end of the sheath may abut against a vessel section or scrape against the inner vessel walls as the sheath attempts to follow the guide wire through sharp turns. As a result, the outer sheath can weaken or damage the blood vessel or release embolic debris or plaque further down the bloodstream. Second, the applications and treatments using conventional sheaths may be limited since it may not be possible to insert the sheath through narrow or curved vascular cavity sections to an aneurysm site. Consequently, the aneurysm or containment site can be left untreated or can be treated while causing damage to other blood vessel sections, in the process possibly leading to more serious injury, stroke and death. These problems are amplified with smaller vessels and vessels having sharp turns and when larger implants are utilized. Third, implants may not be properly retained within an aneurysm as a result of the width or the aneurysm neck. For example, an implant may be improperly secured or inadvertently released from the aneurysm as a result of slipping through a wide aneurysm neck.
A need, therefore, exists for a method and system that permits a delivery sheath and an implant, such as a vaso-occlusive implant or an embolic containment implant that facilitates delivery of a vaso-occlusive implant, to be maneuvered through various vascular spaces so that the implant is deployed at the proper location, such as an aneurysm, tumor, while reducing or minimizing damage to the vascular space and allowing implants to be secured or retained within the aneurysm.